What are Protozoas

Schistosomiasis

Flatworm transmitted to humans in fresh contaminated water.

Eggs shed in feces or urine
Hatch in fresh water
Develop into cercaria in snails
Penetrate human skin (dermatitis)
Migrate to portal blood/mesenteric veins/venous plexus and mate (serum sickness like illness 4-8 weeks after skin invasion can see lymphadenopathy and hepatosplenomegaly)
Eggs produced and circulate in venous blood through liver
Released to intestines/bladder to expel and infect more hosts

Chronic disease you see granulomatous/fibrotic changes in the liver/bladder due to eosinophils and reaction to deposited eggs

Challenges to preventing parasitic diseases?

Public Health strategies for controlling schistosomiasis

building wells/latrines, providing potable water, preventing contamination of environmental water, education about disease, use of molluscides to control snail hosts and treatment with drugs like praziquantel. Vaccination?